This invention relates to solar hot air balloons and more particularly to a maneuvering system for a solar hot air balloon.
Hot air ballooning has become an increasingly popular sport in recent years. In virtually all balloons, the hot air required for buoyancy is generated by a burner which uses propane as a fuel. Typical flight durations with these balloons are from one to two hours. However, by carrying a very heavy overload of fuel, a few flights over twelve hours have been possible. These long flights are for special record-breaking attempts and are not practical for the sport ballonist.
While relatively short flights of one or two hours may be acceptable to many balloonists, it would be most desirable to make longer flights as is commonly the case with gas balloons such as those containing hydrogen or helium. With gas balloons, typical flight durations are more in the range of five to fifteen hours. To make hot air balloons fly, it is necessary to heat air within the balloon sufficiently so that the mass of internal air is less than the mass of the surrounding air by an amount equal to the mass of the balloon and its load. In addition to heating the air with propane or other sources of fuel, it has been known to use solar energy to heat balloons. It is a natural consequence of flying during sunlight hours that some energy will be absorbed by the balloon skin, particularly if it is dark colored, making some contribution toward heat build up. In most cases this is trivial or insignificant.
In my co-pending application Ser. No. 860,711 a solar powered hot air balloon is disclosed having an envelope with an opaque portion and a transparent portion. The opaque portion has a substantially black inner surface which is positioned so as to receive a maximum sunlight radiated through the transparent portion. With such a solar powered hot air balloon, the internal heating of the air within the envelope is dependent upon the rotational position of the envelope about its vertical axis relative to the position of the sun. When the transparent portion faces directly towards the sun, maximum heating occurs.